Cut out for series lamps



y 10, 1932- I c. SEVERIN ET AL' ,857,

cu'r-ou'rron sums LAMPS Filed Sept. 29. 1950 flan/EN TUBE LIARL 5E vrazzsz,

LEUR PETERS,

- BY Mum H25 ATTURJVEY Patented May 10, 1932.

UNITED s TATEs$ cam. snvnam, or CLEVELAND arrears, mnmo afrnm. or- CLEVELAND, omo.

PATENT em e ASSIGNORS TO GENERAL ELECTRIC COMPANY, LA CORPORATION 01 NEW YORK CUT OUT FOR SERIES LAMPS Application filed Se tember 29, mo. Serial No. 4mm.

Qur invention relates, to electric lamps adapted 'to be operated in series and more particularly to means whereby one or more of such lamps may be cut out upon failure thereof without extinguishing the remaining lamps of the series. Still more particularly, our invention relates to'such means in combinationwith the other elements of an electric incandescent lamp. The features and advantages of our invention will appear from i the following description of a species thereof and from the accompanying drawin s. The scope of. our invention is' indicate in the claims appended hereto.

In the drawings, Fig. 1 is an elevation of an electric incandescent lamp embodying our invention, and Fig. 2 is an elevation of a portion thereof on a larger scale. 9

The specific electric incandescent lamp illustrated in the drawings is of the type used for decorative purposes such as Christmas tree ornamentation. It comprises the bulb 10, the base 11 and sealed in the bulb is a mount comprising the leads 12 held firmly by the insulating bead 13 but extending therebeyond to support and. afford electric conduction to the filament 14. Such lamps are usually mounted in sockets connected in series, for instance, a'string of eight so connected is commonly used. When one or more of the lamps of the series burns out, the whole series would be extinguished but for a cut-' out such as that of our invention, which is provided in each lamp. Such cut-outs are normally non-conducting but when the lamp fails, the voltage impressed across the cut-out is sufiicient to break through the insulation normally provided thereby and a conductive path is provided through the lamp which has failed so that the other lamps may still burn. As shown in the drawings, our cut-out in its preferred form comprises a spiral sprin 15 of metal, the turns of which engage eac of the leads 12 and make close contact therewith. The leads are of nickel or copper and have a film of oxide or other comparatively non-conducting material thereon. This film ma beforme on the wire by heating and, in ict, suflicient oxide is formed on the leads to during the fusion of the head 13 there around.

. N ickelchromium alloys or tungsten are par ticularly desirablefor the wire 15 on account of their high resistance althou h there are many other metals and alloys w ich ma be used. So-called nichromd is a nickel-c ro- 1 niu'm alloy which has a high resistance and [is well known as a heatin resistance element.

It is preferred to have t e resistance of the portion 15 of the cut-out fairly high so that the remaining lamps are not given too high a voltage. It-may be desirable to provide beads 16 of insulating material, such as sodium silicate, which are placed around the leads and adjacent turns of the cut-out to hold the latter firmly inposition' What we claim as new and desire to secure by Letters Patent of the United States, is

1. In an electric lamp or similar device adapted to be used in series with other lamps or devices comprising a bulb and leads sealed thereinto, a cut-out comprising a metal con-.

ductor of 'sufliciently high resistance to premaking close contact with anoxide film on at least one thereof.

3. In an electric lamp or similar device comprising a bulb and leads sealed thereinto, a cut-out comprising a spiral spring metal conductor of'high resistance having a pair of turns thereof gripping each of said leads and making close contact with the oxidized surface thereof.

4. In an electric lamp or similar device comprising a bulb and leads sealed thereinto, a cut-out comprisin a conductor consisting of nichrome exten ing between said leads and makingclose contact with an oxide film thereon.

5. An electric-lamp or similar device-come prising a bulb and'leads sealed thereinto, a

cut-out comprising a spiral spring composed of metal of high resistance and having a pair of turns thereof gripping each of said leads andbeads of non-metallic insulating material fused around portions of said leads and metal spring to hold the latter firmly to said leads.

In witness whereof we have hereunto set our hands this 25th day ofSe tember, 1930.

- CARL EVERIN.

LEO R. PETERS. 

